Probably the biggest of those fish is that giant part of the world economy known as Asia. The chart below shows the anticipated growth in numbers of the middle class throughout the world over the next two decades. The solid green circle is the current middle class population (or as at 2009 to be precise); the wider blue-fringed circle represents the forecast size of this population in 20 years' time. The OECD definition of middle class is those households with daily per capita expenditures of between $10 and $100 in purchasing power parity terms.

Note that in the US and Europe, the size of the middle class is barely expected to change over the next two decades. Central and South America, and the Middle East and North Africa, are forecast to grow a little. But one area stands out: the emerging middle class in Asia is forecast to explode, from roughly 500 million to some 3 billion people.

In equity investing, the combination of a compelling secular growth story and compellingly attractive valuations is a very rare thing, the sort of investment opportunity that one might only see once or twice in a generation, if that. But it exists, here in Asia, today. Once again, however, we have to abandon conventional financial thinking in order to exploit it.

David Fuller's view

This is a very good issue of Tim Prices' letter and I commend it to you.

Wall Street's market performance has received most of the headlines this year but it is somewhat overvalued. I really like it for the long term, due to its growing lead in the field of technology, its competitive energy situation, and its number of Autonomies. However, its next few years are very likely to be less rewarding that what we have seen in 2013.

Interestingly, all of Asia's stock markets are now cheaper than the USA and most of them are considerably cheaper. It usually pays to nibble on these occasions. I currently have three favourites.

1) Japan (weekly & daily) which is in the latter stages of its first medium-term consolidation above the base. Japan has a high-tech economy and is taking decisive steps to recover from a 22-year economic malaise following its burst bubble in 1990, including weakening the yen (shown inversely against the US dollar). Japan is far less expensive than Wall Street on the basis of book value. Best case: having ended the secular bear market, Japan is completing the first year of what could become a secular bull trend. Biggest risks: energy costs and conflict with China.

2) China (weekly & daily) has its lowest valuations in years but the Shanghai A-Shares Index is still in the starting blocks, due to supply and domestic investor apathy towards the stock market. However, the Shenzhen B-Shares Index (weekly & daily) is more reflective of the private sector and is still relatively cheap at a p/e of 11.14 and yield of 1.94%, while challenging its historic highs. Best case: a medium-term upward break and strong growth in consumer sectors as China's economhy firms once again. Biggest risks: corruption, misguided central policy decisions and dangerous pollution.

3) Vietnam (weekly & daily) should be in the latter stages of its multiyear base extension phase. Export-led economic growth is improving following the extensive devaluation. Valuations are attractive at a p/e of 12.53 and yield of 3.85%. Best case: should benefit from an increase in Asia's growth. Biggest risk: governance is often a problem in frontier markets.